1. Field of the Invention
This invention relates generally to systems and methods for transmitting and receiving signals such as digitized audio and control signals. More particularly, this invention relates to wireless transmission of digitized audio signals to a remote station and the transmission of remote control signals from the remote station to control the source of the audio signals. The transmission of the digitized audio signals and the remote control signals are on a half-duplex channel.
2. Description of Related Art
The wireless transmission of audio signals is well known in the art. Portable or cordless telephones transmit and receive digitized audio signals between a base station and a portable remote handset. Further, wireless headphones and wireless speakers are commonly used for audio entertainment or television systems.
In the case of the portable or cordless telephones, the system transmits from the base station on one channel or frequency and the handset or remote station transmits on a separate channel or frequency. This is commonly referred to as full duplex operation. Alternately, the wireless headphones normally do not have any transmission capability and only receive the transmissions from the audio entertainment systems. Control of audio entertainment systems often occur with a separate remote control of the type that uses infrared communications unrelated to the transmission for the headphone or speaker. In both cases, this type of communication is commonly referred to as simplex communication.
Some wired headphones for entertainment systems such as portable compact disc (CD) players have additional wiring within the headphone cabling to allow for remote control with a separate set of control switches for the CD player. The control function is attached to the wiring only and has no relationship to the headphone function.
U.S. Pat. No. 5,619,582 (Oltman, et al.) describes an audio enhancement system. Wireless headphones include a transmitter and a receiver. The receiver has a synchronization device that utilizes electromagnetic locating signals to locate the position of the receiver with respect to the transmitter.
U.S. Pat. No. 5,794,127 (Lansang) details a headphone remote control for operating an entertainment center. The headphone includes a fully equipped remote control for privately operating and controlling an entertainment center. The inventive device includes an antenna receiver, a channel selector control, a locator speaker, a locator over-ride circuit, a pressure switch, and a head phone transmitter for transmitting channel and function selection to the entertainment center.
U.S. Pat. No. 6,006,115 (Wingate) details wireless headphones for entertainment and telephonic communication. Wireless headphones receive radio frequency transmissions from a sound system to provide music and other audio programming to a user who is free to move anywhere within the range of the transmissions. The headphones may also incorporate a microphone so that the user can receive the phone call with the headphones, indicating both a transmitter and receiver present in the headphones.
U.S. Patent Application 20020102949 (Langer) describes an entertainment system remote control with an audio port. The remote control has a set of input controls to control an electronic device, including a volume control that is used for entering commands that control the electronic device. The commands are sent to the electronic device using a transmitter. The remote control includes an integral receiver capable of reproducing a digitized audio signal received from the electronic device. The audio output is presented to a port for a headphone jack. When a headphone jack is inserted into the headphone port, the remote control transmits a mute command to the electronic device. Once a headphone jack is inserted into the port, the volume control is configured to control the audio output of the remote control.